"to indulge (another), to minister to base passions, cater for the lusts of others," c. 1600, from pander (n.). Meaning "to minister to others' prejudices for selfish ends" is from c. 1600. Related: Pandered; panderer; pandering.
"arranger of sexual liaisons, one who caters for the lusts of others," 1520s, "procurer, pimp," from Middle English Pandare (late 14c.), used by Chaucer ("Troylus and Cryseyde"), who borrowed it from Boccaccio (who had it in Italian form Pandaro in "Filostrato") as name of the prince (Greek Pandaros), who procured the love of Cressida (his niece in Chaucer, his cousin in Boccaccio) for Troilus. The story and the name are medieval inventions. The name turns up in ancient Greek, but without the story; in Homer he is a Lycian participant in the Trojan War. The name is thus perhaps non-Greek. Spelling in English was influenced by the agent-noun suffix -er.
1530s, "a boisterous, brutal fellow, one ready to commit any crime," from French rufian "a pimp" (15c.), from Italian ruffiano "a pander, pimp," of uncertain origin, perhaps from a Germanic source related to rough (adj.), but Dutch roffiaan, German Ruffian are said to be from French. Whatever its ultimate source, the English meaning of the word might have been influenced by the similarity of the sound to rough. Related: Ruffianly.
The Romanic words (such as Medieval Latin ruffianus, Provençal rufian, Catalan rufia, Spanish rufian) preserve the sense of "protector or owner of whores," a sense occasionally met in English in 17c. For sense evolution in English, compare bully (n.). Related: Ruffianage; ruffianhood; ruffianism.